How Often to Water New Grass Seed?

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We all know that new plants need water to start to grow and that seeds require it to germinate.  When the plant in question is grass, the same principles apply.  But there’s also the issue of overwatering it – too much can be as bad as not enough!

So let’s look at how often to water new grass seed and get a clear idea of when to water those little seeds so they sprout into a luscious lawn.

Watering grass seed – the theory

Before we start, let’s take a moment to look at some grass seed basics, those fundamentals that apply to many types of plant grown from seed but that are worth recalling before we start.

All seeds need moisture and a certain temperature to germinate or start to grow.  Once they start growing, if the conditions change then the seeds can just die off.  This is particularly true if it doesn’t get enough water.

Most grass seeds germinate in 5-30 days so this is the crucial window.  This is when you can first start to see it appearing through the soil.

But if you water too much, you can simply wash the seeds away.  This can lead to clumps or bare patches.  If you are walking on a very wet lawn area, you are likely to either carry off seeds with you or squash them too deeply into the soil.

How often to water new grass seeds

So you know you need to water your grass seeds but not too much.  So how often do you water new grass seeds?

There are a few situations to consider and factors to remember.  How much shade and sunlight the seeds receive can help you decide how much water to use.  If it is raining will also obviously play a part.  If there’s been heavy rain, you probably don’t need to water at all.

But there are three main situations to consider:

An existing lawn with new grass growing through

In this situation, you should water the lawn deeply but infrequently normally but water it every day when there’s new seeds growing.  Use an automatic timer or an app on your phone and water for 5-10 minutes early in the morning and again at mid-day.

Ideally, avoid a sprinkler system and use a hose-end sprinkler or a watering can and aim to apply the water evenly.  Once the grass is showing, reduce it to once a day.

Bare lawns that are being patched

If you have a lawn of a good size with some bare areas, then the basics are similar to the above.  If the area is a small one, you probably can just water it by hand and can often be watered just once a day.

New lawn covered completely with seeds

When you lay new lawn areas completely, you will want to till the soil first to make sure it is loose enough for the seeds to grow.  This means the soil is looser than other situations and the seeds can more easily wash away.

Aim to keep the top inch of soil moist at all times, water 2-6 minutes or longer if needed.  The aim is to be moist but not soggy and may need to be done 2-3 times a day, depending on conditions.  Don’t water for long periods.

Best time of day to water grass seeds

The time of day to water grass seeds is more important than with other more established plants.  You want to avoid watering at the warmest parts of the day because the water will simply evaporate before it soaks into the ground.

The best time to water is first thing in the morning, the coolest part of the day.  If you can’t manage this or need to water more than once, late afternoon is the other good window.  Avoid watering at night as this can create an opportunity where mould and fungus can grow and affect your lawn.

Other tips for a lush lawn

There are a few other tips to help you get those seeds growing well and a new lawn appearing.  These include:

• Avoid the hottest part of the year as a time to plant seeds as this will make watering them even more difficult
• Watch new areas of grass during those hot months to make sure it doesn’t get too dry
• If there are shaded areas and you can see moss or algae growth, reduce the length and frequency of watering
• For small patching projects, pick grass seeds that have a moisture retention coating – they are more expensive but it works out better if you are only seeding a small area
• Go for a good quality lawn sprinkler as cheaper ones tend to be erratic in their water distribution
• Oscillating sprinklers are a good option where the garden has a lot of runoff as their movement lets the water soak in before it is re-watered

Should you add mulch? 

Mulching is the use of something like straw, compost or even a plastic sheet to cover seeds.  It is used in lots of situations to help give seeds a good start and protect them from the weather and from birds.

When it comes to mulching grass seeds, compost is a good option.  This lets the water get through and the nutrients in the compost feed the seeds as they grow.  It also protects them from those pesky beaks.

Aim to have ¼ to ½ inch with compost or if you want to use straw, cover about half of the area with seed in it.

Encourage those grass seeds

With the right watering schedule, you can easily encourage grass seeds and have a healthy lawn or repair those bald patches.  Just remember to adjust according to the weather and to keep checking that everything seems to be growing correctly.